In the art of effecting pasteurization of the contents of closed containers it is common to cause the containers to travel through a closed chamber where the temperature of the containers varies in such a way as to gradually elevate the temperature of the contents to the pasteurizing temperature level and to thereafter gradually reduce the temperature of the contents to a level where the containers can be safely returned to ambient conditions. Commercially available apparatus for accomplishing the foregoing sequence in effecting pasteurization is disclosed in the prior art by Herold et al in U.S. Pat. No. 2,282,187 which issued May 5, 1942. This patent relates to pasteurizing the contents in containers by subjecting the same to successive sprays of liquid to preheat, pasteurize and cool the containers. The disclosure made by Herold et al provided for a gradual temperature change in the containers as they are caused to pass from temperature zone to temperature zone, and in proceeding in this manner a considerable quantity of live steam heat must be supplied in order to maintain the pasteurizing liquid at the required pasteurizing temperature.
An improvement was disclosed in U.S. Pat. No. 2,466,769 by Herold et al which issued Apr. 12, 1949. The disclosure in this patent is directed to a system whereby a small size pasteurizer could efficiently and economically perform all of the functions of varying temperatures of traveling containers by the economical use of hot and cold temperature regulating fluids. However, the disclosure called for the use of large quantities of live steam in order to obtain the desired temperature levels.
The assignee in the case of the above mentioned Herold et al U.S. Patents made and sold single deck and double deck pasteurizers embodying regenerated systems by interchanging water between heating and cooling zones so as to obtain an economical use of live steam and water. The regenerative system obtained economy in the use of steam and water by a counterflow of hot water against cool product at the load end of the pasteurizer and cool water against hot product at the cooling end of the pasteurizer. The pasteurizers as just above described were available commercially in about 1953 with respect to the regenerative system.
These examples of pasteurizers did not provide means for obtaining a thermal balance when skips occur in the supply of containers. Skips in the supply of containers upset ideal heat exchange considerations, but through the provision of means for conserving the use of heated fluid or steam so as to compensate for skips in the supply of containers thermal balance can be maintained, and such provisions have been disclosed in the application of James K. Huling, Ser. No. 062,693 filed Aug. 1, 1979.